Abstract: There is provided an optical transceiver including a laser light source configured to transmit a first optical signal via an optical transmission member having optical fibers, a photodetector configured to receive a second optical signal via the optical transmission member, a visible light source configured to emit visible light which is incident to the optical transmission member, and a control circuit configured to, when the photodetector detects not to receive the second optical signal, control the laser light source to stop transmitting the first optical signal and the visible light source to start emitting the visible light.

Abstract: An optical waveguide connector including a surface having an insertion hole that is connectable to a waveguide by inserting an end portion of the optical waveguide, the insertion hole having a bottom surface, the bottom surface being capable of being bonded with an end surface of the optical waveguide by using an adhesive, and a first convex portion located on the bottom surface of the insertion hole, the first convex portion including an incident surface that receives light from the optical waveguide, the incident surface being larger than an end surface of a core of the optical waveguide to be inserted.

Abstract: An optical module includes a lens sheet having one or more lenses, a substrate having a photoelectric conversion device mounted on a first face thereof and having a first penetrating hole formed therethrough between the photoelectric conversion device and the one or more lenses, and an adhesive layer configured to bond a face of the lens sheet to a second face of the substrate, wherein the adhesive layer has a second penetrating hole formed therethrough between the one or more lenses and the photoelectric conversion device, and a pathway is provided to connect a space constituted by the first penetrating hole and the second penetrating hole to an outside of the space.

Abstract: There is provided an optical transceiver including a laser light source configured to transmit a first optical signal via an optical transmission member having optical fibers, a photodetector configured to receive a second optical signal via the optical transmission member, a visible light source configured to emit visible light which is incident to the optical transmission member, and a control circuit configured to, when the photodetector detects not to receive the second optical signal, control the laser light source to stop transmitting the first optical signal and the visible light source to start emitting the visible light.

Abstract: An optical device includes: an optical element with a surface including one of a light-receiving portion and a light-emitting portion; a resin layer provided over the one of light-receiving portion and the light-emitting portion; and a resin lens provided over the resin layer, wherein the resin layer includes a first shape larger than a second shape of the resin lens in a direction parallel to the surface.

Abstract: An optical module includes a lens sheet having one or more lenses, a substrate having a photoelectric conversion device mounted on a first face thereof and having a first penetrating hole formed therethrough between the photoelectric conversion device and the one or more lenses, and an adhesive layer configured to bond a face of the lens sheet to a second face of the substrate, wherein the adhesive layer has a second penetrating hole formed therethrough between the one or more lenses and the photoelectric conversion device, and a pathway is provided to connect a space constituted by the first penetrating hole and the second penetrating hole to an outside of the space.

Abstract: An optical device includes: an optical element with a surface including one of a light-receiving portion and a light-emitting portion; a resin layer provided over the one of light-receiving portion and the light-emitting portion; and a resin lens provided over the resin layer, wherein the resin layer includes a first shape larger than a second shape of the resin lens in a direction parallel to the surface.

Abstract: An optical device includes: an optical element with a surface including one of a light-receiving portion and a light-emitting portion; a resin layer provided over the one of light-receiving portion and the light-emitting portion; and a resin lens provided over the resin layer, wherein the resin layer includes a first shape larger than a second shape of the resin lens in a direction parallel to the surface.

Abstract: An optical waveguide connector including a surface having an insertion hole that is connectable to a waveguide by inserting an end portion of the optical waveguide, the insertion hole having a bottom surface, the bottom surface being capable of being bonded with an end surface of the optical waveguide by using an adhesive, and a first convex portion located on the bottom surface of the insertion hole, the first convex portion including an incident surface that receives light from the optical waveguide, the incident surface being larger than an end surface of a core of the optical waveguide to be inserted.

Abstract: A drive circuit that drives a light emitting element coupled to a first output terminal of a differential circuit, the drive circuit includes: a dummy load provided at a second output terminal of the differential circuit, a resistor coupled between the first output terminal and the second output terminal, two transistors coupled to a voltage source and applying a current to the light emitting element and the dummy load, and a comparative amplifying circuit having a non-inverting input terminal coupled to a reference voltage, an inverting input terminal coupled to at least the first output terminal of the differential circuit via a resistor, and an output terminal coupled to gates of the two transistors.

Abstract: A method of manufacturing a printed circuit board, the method includes: forming an electrode layer on one surface of a substrate; forming a through hole that penetrates the substrate and the electrode layer, wherein an inner diameter of the through hole in the electrode layer is smaller than an inner diameter of the through hole in the substrate; dropping a curable liquid that has a liquid-repellency with respect to the substrate, on a substrate portion in the through hole from an opposite side to the electrode layer; and curing the liquid dropped on the substrate portion in the through hole to form a lens.

Abstract: A multiplex circuit includes a plurality of input transistors that correspondingly receive a plurality of input signals of different switching points; a plurality of common base transistors, each common base transistor corresponding to a respective input transistor and having an emitter that is connected in series to a collector of the respective input transistor; and an output end that is connected to a collector of each of the common base transistors, and to which a signal that is obtained by combining signals output by each of the input transistors based on the plurality of input signals.

Abstract: An optical connector comprising a connector body, an enclosure that is a slit-shaped hole formed from one surface of the connector body into the connector body and accommodates a sheet-like optical waveguide with a tip of the optical waveguide abutting against a bottom of the hole, and a pressing section that is provided on a first surface of the enclosure facing a sheet surface of the enclosed optical waveguide and presses the enclosed optical waveguide toward a second surface of the enclosure facing the first surface so as to bring the enclosed optical waveguide into contact with the second surface.

Abstract: A light emitting element drive circuit includes: a plurality of signal paths that respectively propagate a plurality of signals obtained by branching an input signal, a plurality of filters different in a frequency band to pass a signal; one or more amplifiers configured to amplify a signal, one or more delay circuits configured to delay a signal, and an addition circuit that adds a plurality of signals, the filter different in the frequency band being arranged in each of the plurality of signal paths, the delay circuit being arranged in one or more of the plurality of signal paths relatively low in the frequency band, the amplifier being arranged in one or more of the plurality of signal paths relatively high in the frequency band, and an output end of each of the plurality of signal paths being coupled to the addition circuit.

Abstract: An optical device includes: an optical element with a surface including one of a light-receiving portion and a light-emitting portion; a resin layer provided over the one of light-receiving portion and the light-emitting portion; and a resin lens provided over the resin layer, wherein the resin layer includes a first shape larger than a second shape of the resin lens in a direction parallel to the surface.

Abstract: An optical connector comprising a connector body, an enclosure that is a slit-shaped hole formed from one surface of the connector body into the connector body and accommodates a sheet-like optical waveguide with a tip of the optical waveguide abutting against a bottom of the hole, and a pressing section that is provided on a first surface of the enclosure facing a sheet surface of the enclosed optical waveguide and presses the enclosed optical waveguide toward a second surface of the enclosure facing the first surface so as to bring the enclosed optical waveguide into contact with the second surface.

Abstract: A multiplex circuit includes: a plurality of input transistors that correspondingly receive a plurality of input signals of different switching points, the switching points beginning with edges of symbol periods of the plurality of input signals; one of a common base transistor that is connected to a collector of the input transistor, and a common gate transistor that is connected to a drain of the input transistor; and an output end that is connected to one of the collector of the common base transistor and the drain of the common gate transistor, and to which a signal that is obtained by combining the plurality of input signals is output.

Abstract: A light emitting element drive circuit includes: a plurality of signal paths that respectively propagate a plurality of signals obtained by branching an input signal, a plurality of filters different in a frequency band to pass a signal; one or more amplifiers configured to amplify a signal, one or more delay circuits configured to delay a signal, and an addition circuit that adds a plurality of signals, the filter different in the frequency band being arranged in each of the plurality of signal paths, the delay circuit being arranged in one or more of the plurality of signal paths relatively low in the frequency band, the amplifier being arranged in one or more of the plurality of signal paths relatively high in the frequency band, and an output end of each of the plurality of signal paths being coupled to the addition circuit.

Abstract: A drive circuit that drives a light emitting element coupled to a first output terminal of a differential circuit, the drive circuit includes: a dummy load provided at a second output terminal of the differential circuit, a resistor coupled between the first output terminal and the second output terminal, two transistors coupled to a voltage source and applying a current to the light emitting element and the dummy load, and a comparative amplifying circuit having a non-inverting input terminal coupled to a reference voltage, an inverting input terminal coupled to at least the first output terminal of the differential circuit via a resistor, and an output terminal coupled to gates of the two transistors.